[Intel-gfx] Workaround for flicker with panning on the i830 - found a way for tiled displays

[Daniel Vetter]

On Fri, Nov 15, 2013 at 02:16:11PM +0100, Thomas Richter wrote:
> Hi Daniel, hi others,
> 
> did even more experiments. I guess I understand now better. Indeed,
> the trouble seems to be the watermark levels. I played more
> with all that, and the real culprit seems to be the FW_BLC register
> controlling the watermarks.
> 
> On the i830 with the current settings, it is defined to be 0x1080304
> which sets the watermark a bit too low. If I set it to
> 0x1080306 instead, I get a stable display in all panning positions
> (hurray!).
> 
> I would like to fix this, but I guess I would need to understand the
> logic a little bit better. At the time being, you probably better
> put the linear frame buffer workaround on hold, it looks I really
> got something here.

Gosh, should have read the code more closely. We have a totally botched wm
setup on i830M - the watermark code for the 2nd pipe is just not there!

I'll try to wip up a patch to fix this.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch